2. Use Your Laptop -- First, make sure you have your laptop completely charged. If the power happens to go out, one is able to plug in your phone into your computer via the USB port. This one may seem obvious, but when things are getting chaotic, it can be easy to slip your mind.
3. Stop Running Apps -- I actually just learned this a few weeks ago and my battery life has improved drastically. Even when you are not using some apps, they are still running on your cell phone and running down your juice. If you have an iPhone, you can hit your home button twice and the apps that are running will appear on the bottom of your phone, where you can close them. Also, make sure to shut off Wi-Fi and Bluetooth and opt to text when possible, as it uses less power than calling. Additionally, lowering the screen brightness helps, too.